[vsnet-chat 2706] (fwd) Lanning 420 (JG)

[Taichi Kato <tkato>]

From jgts@jgws.totalserve.co.uk Wed Mar  1 23:04 JST 2000
Date: Wed, 01 Mar 2000 18:04:49 +0000
From: JG <jgts@jgws.totalserve.co.uk>
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To: tkato@kusastro.kyoto-u.ac.jp
Subject: Lanning's UV Objects
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Dear Taicho Kato

I read with interest your note re Lanning 420 on the VSNET pages.

I note that Lanning 32, catalogued as B 15.7 by him, appears to be B
14.8 in 1954.0 USNO A2.0 plates [with 'blue minus red' = -0.7], and
derived BT [Tycho B] 12.0 in AC2000 1895.174 plates [star number
4609901].  Although these various 'blue magnitudes' are not always
directly equatable and/or accurate, these three disparate values are
intriguing.

Checks show that there is no catalogued bllac, agn, qso, D&S CV,
GCVS/NSV/NSVS or other object at this position, nor any GSC star, and
there is definitely nothing that blue nearby in USNO A2.0, although I
concede that this object could already be well known to CV devotees.

A similar but not as convincing circumstance exists for Lanning 73,
except that the USNO and Lanning's B magnitudes agree at about 13.8
[possibly due to using the same plates in this instance?].  The star is
not in the GSC but the AC2000 has object number 492418 of BT 11.9 on
epoch 1902.169 at this position.  However, it should be noted that
experience has shown AC2000 BT magnitudes can easily be up to two
magnitudes different from catalogued Johnson B and B magnitudes for
quite non-variable objects.

The list of Lanning's objects that I was able to obtain only stretched
into the high 300s, and is I believe the 4th edition, so I have not as
yet had chance to test the latest data you mentioned.

Yours

John

John Greaves
UK

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